- Experienced contact lens wearers are appropriate for studies that use their own lenses (soft, rigid gas permeable [RGP], hard [PMMA]) or the same type of lens within the FDA approved modality (daily, continuous or extended wear) and replacement cycle (for example, daily, one week, one month, etc.) as described in the lens package insert and/or prescribed by their eye care provider to investigate ocular surface data before, during and after lens use.